Machine for the electric welding of tubes



Nov. 8, 1938. D. sclAKY 5 MACHINE FOR THE ELECTRIC WELDING OF TUBES Original Filed May 29,-1936 3 Sheets-Sheet l Davicl j INVENTOFQ Q W k Nov. 8', 1938. D. SCIAKY 2,136,059

MACHINE FOR THE ELECTRIC WELDING 0F TUBES Original Filegi May 29, 1936 s Sheets-Shoot 2 IN N R D. SCIAKY MACHINE FOR THE ELECTRIC WELDING OF TUBES Nov. 8, 1938.

3 Sheets-Sheet 3 Original Filed May 29, 1956 vlll/f/ l/ld I. I

- David s k INVENTOR BY {M ATTORNEY.

Patented Nov. 8, 1938 moms FOR T E ELECTRIC wELnmG or roars David Sciaky, Paris, France Original application My 29, 1936, Serial No.

Divided and this application Doom-- her 2, 1938, Serial No. 113,179; In France Ma! This application is a divisional application of applicant's copending application Serial No. 82,485, illed May 29, 1936.

(i. sis-s) One object of the present invention is to provide an improved machine for the resistance welding of tubes in which use is made of roller electrodes contacting with the work to be welded, which is continuously moved forward.

More specifically, the object is to ensure. the direct and also the indirect welding in one single operation. I A further object of the invention is to reduce .to a minimum the expenditure of current used for the weld, and alsoto,increase the speed at which the work is displaced during its passage over the welding electrodes, thus raising the output of the machine. v

Another purpose is to exercise adequate con trol over the welding effected by the electrodes ho andso increase the quality of the weld.

The invention likewise aims at causing the metal to anneal during the welding operation it-- self and at the suppression of internal stresses.

In view of this, the invention renders the opera-' as tions with an annealing furnace superfluous and reduces to a minimum the necessity turnermalizing, thus lowering the pricerof the finished product. 1 a

Furthermore, the invention aims at the prow duction of finished products having a smooth, polished appearance of a bluish colour owing to the avoidance of any coating of black iron oxide which is formed at 300 to 600. The tube is there fore in the optimum condition to take on a highggly adhesive layer of zinc.

Finally the invention aims at providing a welding machine of great simplicity and of the lite most emciency. I The machines whereby the foregoing objects 4 are realized have the features set forth in the following description and in the claims at the end of the said description. v

The preferred constructional form of themvention is illustrated, by way of example, in the vtor the welding roller.

the weld is to be carried out.

machine showing a modification of the support 1 In Fig. 1, the path followed by the current is shown by arrows. I

The transformer 90 supplies on the one hand the upper roller 9! and on the other hand the "two side rollers 92, 93. r

The current input 'is carried out by two rollers 92 and 93 mounted in parallel, while the current output is carried out through a single roller 9| arranged on the gap of the tube to be welded. The flow of the current is obtained according to, the process described in" the application Serial Number 82,485.

The two rollers 92 and 93 are mounted on a carriage 94, which can be adjusted in a direction parallel to that of the tube displacement. The gripping of the tube between the roller 92 and the roller 93 is eilfected by means of the screw 95.

h At the level of the electrode 9i are fitted two pressure rollers 96 and 91, which enable the two sides of the wall of the tube to come closely together in the neighbourhood of the point where These two rollers can be adjusted by means of the screw 98. The whole unit comprising these two rollers is also mounted on a carriage 99, the position of which can be adjusted. The tube blank, which has been suitably prepared, passes under a guide roller .ltll before passing between the two current-feed rollers 92 and 93. Immediately afterthe weld has been'completed, the tube is guided by an adjustable roller lot, which can be set in all directions, and a scraping tool it! completes the operation by removing any excessive burrs. H t

The pressure of the electrode 95 is efiectedby a lever system I03, the whole of which is suspended on' a carriage lM. r

The position of the carriage m which supports the electrode 98 may be made parallel to the tube by means of the screw 05. A

All the operative members can be regulated independently of one another and the distance separating the two up-stream rollers 82,. $3 from the downstream roller ti may be varied at will. Similarly, the lateral rollers may have their pressure modified, while the position of the pressure rollers relatively to the welding roller can also be altered.

The tube blank may be disengaged from the machine with great ease.

The whole unit is mounted on a frame I08,

which is integral withthe chassis till, which supports the transformers. v

' For the sake of greater clearnesathe diagram showing the circulation of the water that cools the different elements of the machine is not given;

also the control switch which enables the weld- 3 ing current to be regulated has also been omitted.

In Fig. '2, there is represented separately and in its practical constructional form, the mechanical pressure device 8|. The lever 28 is guided by the rod 38 which slides in the support 48. A

nut 4|, screwed on rod 88, allows of limitation of the travel of the rod and, consequently, of the roller 9| also, by the nut 4| bearing on the bottom of the hole 42. In this way the roller 8| is prevented from dropping into the gap in the tube whenever, for any reason, the heated metal should give way and open under the pressure of the roller 8|. The amount of play indicated at 43 determines the total upward travel of the roller 9! against the pressure of the spring 28. The hand-wheel 84 permits, in turn, of lifting the roller from the tube blank by rotation of the screw 88, the upper extremity of which bears on the rotating stop 82. The wheel 8| enables the pressure of the spring 28 to be regulated. In order that the degree of pressure of the latter may be apparent, there is provided a dial 44 over which moves a pointer integral with a pinion 45 engaging with a rack 48, whose vertical displacement .corresponds to that of the handwheel 8| as it is screwed up or down, and inconsequence, the linear value of the compression of the spring 28 is indicated. It is seen that it is possible to raise the roller 8| instantly from the work by turning the handles 84 without the pressure determined by the hand-wheel 8| being affected.

Fig. 3 shows in detail the welding roller or I disc 8|, the guiding-means and the arrangement for supplying current to this roller and for the circulation of water-round the electrode.

The disc 8| is-secured on a hollow spindle 48 by means of bolts and nuts 41. This hollow spindle also carries, at the same end, the cupshaped member 68 which is secured on the boss 48 by means of a cap 8.8 screwed on to the boss which has its end screw-threaded. The spindle 48 also has an internal tube 82, which is secured to the ring 8| screwed into the opposite end of the hollow spindle 48. The spindle 48 has an enlarged portion 480 and is surrounded by a stationary drum 88 within which it can rotate. A space or chamber 84 is formed between the enlarged portion ofthe shaftami the inside of the drum 58.

This chamber .88 is made leakage-proof by joints 55 and Sfwhich are constructed and arranged so as not to oppose the rotation of the hollow spindle 48. The drum 88 is kept filled with mercury which is inserted through plug 81, while another plug IO-enables the mercury to be drained out when The joint betweenthecflpindle and its support consists of agband of'plaited asbestos n, wound in one or ;seweral layers around a cylindrical part 14 of iihe spindle 4:. On this bandjggfl tted a ring of flexible rubber 18, which in virtugpf its extensibility, may be slipped over the enlargement 48a. vWhen the bearing 88, which is in two halves, is put in place, this ring 81 is compressed in its position. This joint ensures a perfect tightness as the rubber exerts an even and constant pressure on the asbestos, prevents the mercury fromv being pressed over the sides, and at the same time allows of ,the spindle sliding very smoothly.

- tionary nozzle 88 for the supply of water.

The drum 88 is formed, on the outside, with two tapering recesses 88 and 88a, within which are mounted the thimbles 88 and 88d of the current supply leads, the thimbles being secured in place by studs 8|. Within these thimbles are welded the extremities of the conductors coming from the secondary of the welding transformer.

The current flows through these thimbles and then through the member 88 and the mercury bath contained in the chamber 84 and thence to the spindle of the welding electrode and to the latter itself. In this way contacts as satisfactory as possible are maintained, there is no leakage from the mercury enclosure and there is a minimum friction on the spindle of the electrode.

The water for cooling the electrode is supplied through a nozzle 82, which is screwed into the stationary part 88, the tightness between the rotating and the stationary parts being maintained by the Joints 84 and 88 which are subject to the action of a spring 88.

The water passes into the interior of the tube 82, then into the channels 81 cut in the plug 48 and circulates'within the chamber 88, this cooling the electrode 8|. The water is then discharged through the channels 88 and the space 18 formed between the inside of the member 48 and the outer wall of tube 82, so as to pass through the aperture cut in the ring SI, and, by a pipe connection, into the chamber 12 so as to cool the ends of thethimbles 88 and also the partition 88 surrounding the mercury bath. The water is finally discharged through a side pipe 8 The member 48, 48a is made of an alloy of copper.

In order toprevent the mercury from acting on the ,parts with which it comes in contact and causing leakages, the surfaces in contact with the mercuryare covered by a metal immune from attack by the latter, such, as, for instance, an electrolytic layer of chromium.

In Fig. 4 are shown the two up-stream" roll,- ers with the arrangement for the supply of current andvof cooling water. The two rollers 82, 88 are carried by two supports I8.

Each spindle 18 is secured to a roller by bolts. At its upper extremity it is formed as a cup 88, filled with mercury. This spindle and its cup thus participate in the rotation of the roller. A conducting member 8| dips, by its two curved extremities into the two cups of the two spindles 18. The member 8| is provided, at its upper end, with a semi-cylindrical surface on which is secured by the cover 82 and its fixing bolts, a cylindrical, current-conducting rod 88 which connects the member 8| with the pole of the transformer opposite to that of the welding roller (Fig. 8).

Each of the spindles 1a is hollow and receives cooling water by way of a pipe 84 screwed into its upper end and on the end of pipe 84 there bears under the influence of a spring 88, a sta- Apertures 81, cut in the rollers 82, 88, allow of the cooling water flowing out. The rod 88 is itself hollow and is also cooled by water circulation. The same arrangements as for the members 88 and 48a in Fig. 3 are taken to protect their surfaces from the action of mercury. The play allowed for at 88 enables the two rollers (and their integral member) to shift their positions relatively to each other without the stationary member 8| being afl'ected. The cover 88 protects the mercury from outside influence.

aunt-om Figs. 5 and 6 illustrate an improved modification of a device according to the present invention, which modification comprises a pair of side pressure rollers I50 having a certain difference of potential relatively'to the welding roller ll.

As in the case of Fig. 1, there are here also the two upstream side rollers 33, 33, the main welding transformer 90 and the single roller electrode arranged "downstream, at the weld- When-the switch I54 is adjusted to a dead stud, no current flows through the secondary winding of the auxiliary transformer I53, and the entire feed current flowsthrough the main transfo mar 96 into the work between the rollers 92, 93 nd roller 3i.

It, on the other hand, the switch I" of the auxiliary transformer I53 isso adjusted as to cause a current to flow in the direction indi- 1 cated by the arrows in Fig. 5 and to regulate the intensity. of this current, the intensity of the current passing through the tube between the rollers d2, 93 and the roller 9i is reduccd,

' and at the same time that of the current passing between the rollers H0 and 9! is increased. The result is a less intense heating of the tube section between the rollers 92, 93 and the roller ti and, on the otherhand, a more intense heating at the exact spot where the welding is to be effected Assuming that the output of the transformer iii] can be regulatedby means of the tap switch i55, there is thus provided a regulating means which is. independent of the heating of the entire tube as well, as of the heating of the gap at the exact spot where the weld is to be effected.

The device illustrated in Fig. 7 is intended to regulate the contacting pressure of the "downstream" or welding roller 9| on the tube, in accordance with variations in the current supply of the'machine. The current supply system of the roller 9| is omitted in Fig. 'I in order to. simplify the drawing.

The welding roller 3| is pressed onto, the tube by means of a spring 28-which acts upon a lever 29 pivoted at 30. A hand wheel 3| serves to regulate the pressure of the spring 28, the reaction of the latter being taken up partly by the tube at the spot where it is contacted by roller 9i (welding pressure) and partly by the abutment 32 in engagement with a collar on thethreaded rod 33, which rod is adjustable by means of a hand wheel 38. On the rod 33 is fitted an iron core 35 subject to the magnetic action of a coil 36 supported on the frame of the machine and connected to the current supply 31 through an adjustable rheostat 33.

The attraction of the iron core 35 by the coil 36 lifts the collar on the-rod off the stop 32 and causes a further compression of the spring 28 whereby the contacting pressure of roller 3| is accordingly increased. The effectiveness of the coil 36 can be regulated bymeans of the rheostat 38.

accordingly reduced with the result that the contact resistance r between the roller 9i and the tube is increased. Simultaiheously the intensity I of the welding current is diminished.

Obviously the coil may be connected to the primary or secondary winding of the transformer of Fig. 1, so that the current will act directly and automatically to compensatefor variations in the temperature of the weld.

The automatic variation of the pressure of the welding rollers, in dependence on' the weldihg current or the tension of the supply voltage may, of course, be effected by means other than those indicated, by way of example, in Fig. '2,

without exceeding the scope of the present in-- vention, the novelty of which resides in the automatic regulation of the temperature of the precise spot where the weld is to be efiected, by

the direct or indirect, partial or total action of the current on the contacting pressure of the welding roller.

I What l2 claim as my invention and desire to secure by Letters Patent is:--

1. In a machine for the electric resistance welding of tubes; means for displacing the work with a continuous translation movement;*

a main welding transformer having a primary winding and a secondary winding for welding; roller electrodes for the supply or the current arranged on the upstream side of the work, connected with one of the ends oi the secondary winding of the main transformer; and a roller.

supply of the current arranged on the upstream side of the work to be welded and connected with one of the ends of the secondary winding of the vmain transformer as well as with one of the ends of the secondary winding of the auxiliary transformer; a' roller electrode disposed on the downstream side over the gap in the work and con-- nected to the other end of the secondary winding of the main transformer; and an additional roller electrode, for regulating and distributing heat, applied on the work and connected with the other endof the secondary winding of the auxiliary transformer.

3. In a machine for the electric resistance welding of tubes: means for displacing the work with a continuous translation movement; a main welding transformer having a primary winding and a secondary winding for welding; roller elec trodes for the supply of current arranged on the. upstream side of the work to be welded and connected to one of the ends of the secondary winding of the main transformer; a roller electrode arranged on the downstream side over the gap in the work and connected to the other end of the secondary winding of the main transformer; a main tapping switch controlling the current feeding the primary winding of the main transformer; and means to regulate the distance between the upstream roller electrodes and the downstream welding roller.

4. In a machine for the electric resistance welding of tubes: means for displacing the work downstream side over the gap in the work and connected with the other end of the secondary winding of the main transformeryan additional roller electrode for regulating and distributing heat, connected to the other end of the secondary winding of the auxiliary transformer; an

auxiliary tapping switch controlling the current feeding the primary winding of the auxiliary transformer; and means to regulate the distance between the upstream roller electrodes and the downstream welding roller.

5. In a machine for the electric resistance welding of tubes, means for displacing the work with a continuous translation movement, a source of electric current, roller electrodes for the supply of the current arranged on the upstream side of the'work piece and connected with one, terminal 01 saidsource of current, and a roller electrode arranged on the downstream side over the gap in the work piece and connected to the other terminal of said source of current.

DAVID scrm. 

